1. Field of the Invention
This invention relates to a process for converting non-alpha-tocopherols to alpha-tocopherol.
2. Description of Prior Art
Various processes are known in the art for converting non-alpha-tocopherols to alpha-tocopherol, a form which has relatively high Vitamin E activity compared to the beta-, gamma- and delta- forms. For example, U.S. Pat. No. 2,592,628 (the disclosure of which is incorporated herein by reference) discloses subjecting tocopherols having at least one aromatic hydrogen atom on the nucleus to formylation to replace the aromatic hydrogen atom or atoms with formyl groups and reducing the formylated tocopherol material, whereby the formyl groups are reduced to methyl groups. Also, U.S. Pat. No. 3,819,657 discloses that non-alpha-tocopherols can be converted to the alpha form using formaldehyde in the presence of orthophosphoric acid (or an orthophosphoric acid generating material) and catalytic hydrogenation. Conversions of as high as 92% are reported in this patent.
U.S. Pat. Nos. 3,122,565 and 3,402,182 disclose use of basic anion exchange resins in the purification or separation of tocopherols.